The present invention generally relates to the field of structural reinforcement devices, and in its preferred embodiments more specifically relates to an interlocking, self-aligning, magnetically detectable reinforcement device structure.
All structural members are subject to deterioration and damage over time, and it is often necessary to repair and/or reinforce structural members to preserve or restore their integrity and extend their useful lives. The problems resulting from deterioration affect pipelines, which are subject to deterioration due to several factors, including sulfate reducing bacteria, cathodic actions, and third party damage. The problem is certainly not limited to such pipelines, and also affects other structures, such as concrete columns, which are also subject to deterioration and to damage. However, the problem is particularly acute for pipelines, because they are difficult to inspect, and carry gases and liquids under high pressure over long distances in extensive systems. Pipeline deterioration can be highly problematic, not only because of economic factors, which are significant, but also because of the potential hazards to the environment and to human safety associated with release of many of the substances transported through pipelines.
Pipelines are typically constructed of metallic pipe, and it has become a relatively common practice to monitor the integrity of pipelines by sending a device, often referred to as a xe2x80x9csmart pigxe2x80x9d, through the line. This device induces a strong magnetic field and records the deviation of the field to establish pipe wall integrity. If a pipeline has developed a significantly corroded area, the resulting anomaly, or lack of continuity, in the magnetic field can be detected. Since the location of the detection device can be monitored or determined, the location of the corroded area can be determined and repaired.
Various approaches to repairing and reinforcing weak areas in pipelines have been developed over the years. Similar approaches are also used for repair and reinforcement of other structural members. In general, the prior art approaches include metallic devices, often in the form of split sleeves, which are welded or otherwise attached to the pipeline around the weak spot; and non-metallic devices, generally in the form of resin impregnated uni-directional fiber tapes that are wound around the pipe and secured by some form of adhesive. Both of these prior art approaches can be reasonably effective, but both suffer from certain problems and drawbacks. The typical prior art metallic repair technology requires welding or other xe2x80x9chot workingxe2x80x9d to attach the device to the pipeline, which may create significant hazards if the fluid carried in the pipeline is explosive or flammable. The welding process, especially in field repair conditions, requires skilled operators, and may nonetheless result in incomplete welds or later weld failures, which can give rise to future pipeline failures. Problems can arise from galvanic action between the pipeline and the metallic repair material. The use of sleeves that are bolted in place around the pipeline also creates problems and results in uncertain repairs. With bolted sleeves, a resilient liner is normally required between the sleeve and the pipe, and sealing of the leak or corroded area depends on the formation of a complete seal at the time of repair and upon the continued integrity of the liner over an extended period of time. Bolted sleeves and resilient liners do not preclude the entry of moisture between the sleeve and the pipe, and any deterioration of the sleeve may allow fluid to escape from the pipeline. As a result of these deficiencies in metallic repair technology, it is often necessary to reduce the pressure of the fluid carried in the pipeline, thereby reducing the flow rate.
Prior art non-metallic repair and reinforcement technology has its own set of problems and difficulties. Typical prior art resin impregnated tapes incorporate unidirectional fibers, which are subject to longitudinal shearing problems. The occurrence of shear compromises structural integrity and also creates an entry point for moisture, which can xe2x80x9cwickxe2x80x9d through the fiber. In an effort to control shearing, a resin filled polyethylene/polypropylene tape is often used to cover leading and trailing edges. However, the tape surface does not effectively bond with existing adhesive systems, and it is difficult to eliminate voids and moisture penetration. Attachment of the non-metallic tape devices of the prior art relies upon the bonding strength of the adhesive used, but it is difficult to ensure uniform adhesive coverage and thus uniform and effecting bonding. The xe2x80x9cwrap patternxe2x80x9d can be difficult to control with conventional devices, leading to variations in coverage and reductions in integrity. A significant disadvantage of the prior art non-metallic technology is its transparency to pipeline detection devices. Even if a repair is adequately made, the repaired location will continue to be registered as a void or leak in the pipeline, creating a monitoring problem, placing a greater burden on the pipeline operators to interpret anomalies previously repaired, and reducing the overall reliability of detection devices in monitoring pipeline integrity.
There remains a definite need for a repair and reinforcement device that achieves desired results without the disadvantages and drawbacks of the prior art, that improves reliability and integrity of the repair or reinforcement, that promotes uniformity in application, that avoids alignment problems, that is safe to use without fire or explosion hazard, and that is detectable by conventional pipeline monitoring devices.
The present invention provides a cured pre-formed composite device for pressure containment, and/or structural reinforcement. The invention encompasses a device formed as a metallic/non-metallic hybrid structure that is magnetically detectable, and also encompasses devices that are self-locking and self-aligning. The device of the invention is less susceptible to shearing than structures known in the prior art, and provides superior corrosion resistance for structural members such as steel piping and concrete columns. The cured pre-formed composite device is applied by wrapping the device, with or without an adhesive, in a plurality of layers around degraded structural members to provide pressure containment and/or structural reinforcement. All voids and/or tented areas in the structural member are filled with a load transfer material prior to installation of the device.
The material of construction of the invention generally comprises a cured metallic/non-metallic composite hybrid, formed into a device for use as structural reinforcement and/or pressure containment. The preferred laminate construction of the device preferably comprises a ferrous or ferrous-based mesh, bands, or sheets of magnetic material or other materials which influence magnetic fields, sandwiched between plies of resin impregnated high tensile strength fiberglass and/or other advanced materials such as carbon/graphite and aramid fibers, pre-formed into a thin multi-ply device detectable by magnetic inspection devices. The magnetically detectable material is sandwiched the entire width or a portion thereof and may be either continuous or intermittently placed along the length of the device. Although the material of the invention may be formed into almost any configuration as appropriate for its intended use, it is contemplated that the material will most typically be formed into generally shape-retentive devices configured as xe2x80x9ccoilsxe2x80x9d. The shape of coils in which the cured pre-formed composite device is formed is determined by the fabrication tooling, and may be cylindrical, or rectangular, or any derivation thereof, depending upon the intended use. Both the width and the total length of the composite device is determined by the shape, size and required reinforcement of the structural member to which it is to be applied.
The invention also encompasses a device in which the surface of both faces of the cured composite material is embossed with a multiplicity of locking serrations or equivalent geometric shapes to interlock layers of the material as they are applied to a pipe or other structure. The serrations, either continuous or intermittent, are preferably oriented perpendicular with respect to the composite laminate length, and thus parallel to the axis around which the layers of the xe2x80x9ccoilxe2x80x9d are formed. The serrations provide a mechanical interlock between layers of the material comprising the device as a means of securing the device. This feature may be used in conjunction with an adhesive, as a redundant system, to ensure device reliability. The embossing of the faces of the device serves to increase the bonding surface of the faces of the device and increases the effectiveness of an adhesive bond.
The invention also provides a structure in which the surface of both faces of the cured composite material are embossed with alignment xe2x80x9cv-groovesxe2x80x9d or equivalent geometric shapes to facilitate alignment of layers of the material of the device as they are wrapped around a structure, such as a pipe. The xe2x80x9cv-groovesxe2x80x9d or equivalent geometric shapes extend, continuously or intermittently, along one or both outer edges, or at any position between the edges, of the preformed composite material, and are oriented parallel to the composite laminate length. The alignment feature ensures that the plurality of layers is consistently deployed in the proper position as the device is applied to a pipe or other structure.
The structure and features of the invention, individually and in combination, provide a structural reinforcement device that is highly effective for its intended use without the disadvantages prevalent in the prior art. The preferred and alternative structures and features of the invention are described in more detail below, with reference to the accompanying drawing figures.